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Gain Characteristics (gain + characteristic)

Distribution by Scientific Domains
Engineering71%
Physics and Astronomy28%

Selected Abstracts

Gain characteristics and lasing of Ga(NAsP) multi-quantum well structures

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2009
C. Lange
Abstract Lasing is demonstrated for a Ga(NAsP) multi quantumwell structure grown pseudomorphically on GaP using metal-organic vapour-phase epitaxy. For a series of temperatures ranging from 8 K to 290 K, the sample emission characteristics are determined. With increasing pump power, a spectral narrowing of the emitted light along with a blue-shift is observed as the lasing threshold is approached. Above the threshold, the emission splits up spectrally into a pattern of clearly distinguishable modes. In addition, the potential of this material concerning roomtemperature lasing is investigated by means of a variable stripe-length experiment, where a modal gain of 10 cm,1 is observed. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Alternative approach to low-noise amplifier design for ultra-wideband applications

INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 2 2007
Qiang Li
Abstract Conventional ultra-wideband low-noise amplifiers require a flat gain over the entire 3.1,10.6 GHz bandwidth, which severely restraints the trade-off spaces in low noise amplifier design. This article proposes a relaxed gain-flatness requirement based on system level investigations. Considering the wireless transceiver front-end with antenna and propagation channel, the unflat-gain low-noise amplifier with an incremental gain characteristic does not degrade the performance of overall system. As an alternative to its flat-gain counterpart, the proposed unflat gain requirement tolerates gain ripple as large as 10 dB, which greatly eases the design challenges to low-noise amplifier for ultra-wideband wireless receivers. Two low-noise amplifier examples are given to demonstrate the feasibility and design flexibility under the proposed gain-flatness requirement. © 2007 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2007. [source]

Meandering probe fed patch antenna with high gain characteristic for circularly polarized application

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2007
Hau-Wah Lai
Abstract A meandering probe-fed circularly polarized stacked patch antenna with truncated corners is studied. The antenna has a wide 3-dB axial ratio bandwidth of 12%. It exhibits a stable radiation pattern across the axial ratio bandwidth. The antenna has low cross polarization and high gain, which are ,14 dB and 10 dBi, respectively. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1095,1098, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22357 [source]

Gain,bandwidth limitations of microwave transistor

INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 6 2002
Filiz Güne
Abstract This work enables one to obtain the potential gain (GT) characteristics with the associated source (ZS) and load (ZL) termination functions, depending upon the input mismatching (Vi), noise (F), and the device operation parameters, which are the configuration type (CT), bias conditions (VDS, IDS), and operation frequency (f). All these functions can straightforwardly provide the following main properties of the device for use in the design of microwave amplifiers with optimum performance: the extremum gain functions (GT max, GT min) and their associated ZS, ZL terminations for the Vi and F couple and the CT, VDS, IDS, and f operation parameters of the device point by point; all the compatible performance (F, voltage,standing wave ratio Vi, GT) triplets within the physical limits of the device, which are F , Fmin, Vi , 1, GT min , GT , GT max, together with their ZS, ZL termination functions; and the potential operation frequency bandwidth for a selected performance (F, Vi, GT) triplet. The selected performance triplet and termination functions can be realized together with their potential operation bandwidth using the novel amplifier design techniques. Many examples are presented for the potential gain characteristics of the chosen low-noise or ordinary types of transistor. © 2002 Wiley Periodicals, Inc. Int J RF and Microwave CAE 12, 483,495, 2002. Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mmce.10049 [source]

An overview on S-band erbium-doped fiber amplifiers

LASER PHYSICS LETTERS, Issue 1 2007
S. W. Harun
Abstract An erbium-doped fiber amplifier (EDFA) for S-band signal amplification is designed by using a depressed cladding erbium-doped fiber (DC-EDF). The fiber's characteristics are described in terms of the effects of the fiber spooling diameter on the amplifier's performance. In this experiment, the spooling diameter required for optimum amplifier gain was around 5,7 cm. By using a typical two-stage configuration (with a 27 m long DC-EDF and a 260 mW pump laser power), the maximum small signal gain obtained was about 32 dB. Yet, by employing a double pass amplifier configuration with a shorter DC-EDF length and a lower pump laser power (15 m and 135 mW, respectively), a similar maximum small signal gain of approximately 30 dB was achieved. This improvement in gain characteristics however, incurred an increased noise figure penalty of about 1 dB in comparison to single-pass amplifier configurations. In order to reduce the amplifier's noise figure while maintaining its high gain, a partial double-pass S-band EDFA configuration was introduced. This configuration provides a high 26.9 dB gain and an improved noise figure comparable to a single pass configuration. Gain clamping in S-band EDFAs are also demonstrated by utilizing a fiber Bragg grating to form an oscillating laser at around 1530 nm. This technique enables good gain clamping with a gain variation of less than 1 dB. (© 2007 by Astro, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source]

An octave-band smooth-wall pyramidal horn

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 4 2006
Krishnasamy T. Selvan
Abstract A smooth-wall pyramidal horn offering satisfactory performance over an octave bandwidth (in the frequency range 4,8 GHz) is reported. While the VSWR is 1.5 or better, the pattern and gain characteristics are also acceptable. The experimental results are presented and compared with those obtained by simulation. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 691,693, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21444 [source]

A low-profile broadband 16-mm-diameter post-type monopole antenna ceiling-mounted in a building

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2004
Yong-Woong Jang
Abstract This paper experimentally presents a low-profile broadband post-type monopole antenna. The characteristics of the antenna are highly dependent on the design parameters (Rm, hm, hfl, and Rg). Instead of a wire monopole, the proposed antenna is made of a 16-mm-diameter aluminum post that is ceiling-mounted in a building. This is due to the low-radiation resistance in the usable band. The post-type element is used to enhance the impedance matching. The experimental impedance bandwidth obtained is approximately 67.9% (1.9824,3.5534 GHz) for a VSWR of less than 2.0. The impedance bandwidth covers multiband operations for mobile and satellite communication. We also present the measured radiation patterns and gain characteristics of the proposed antenna. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 395,397, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20150 [source]